Again, you have to remember the past circumstances which forced these in-love couple to take divorce decision. The return of Sakshi, then Doctor's and other family members' constant warnings regarding her health, Sakshi's reaction at Purvi being Mukhi's molkki despite being unaware of his love for P ......everything was paving the path towards this decision. Moreover, the very realizations that "Sakshi is not in fault but a victim of the fate" and "how the complexities of all these relationships will affect the future of their kids" were hitting them really hard. We saw how these thoughts made Mukhi feel guilty to some extent and thus making him puzzled and perplexed when to choose between bawari and Sakshi. He loves bawari and he is clear in that stand. But his empathy towards Sakshi, his responsibility towards her not just as his former love or his wife but also as the mother of his kids pushed him more into the dilemma where he can't just leave her like that. On the other hand, Purvi being his true soulmate, just wants to put an end to his inner turmoil and to bring him peace, even at her own cost. Well, wouldn't any lover at her place do the same? That's why probably love is called 'sacrifice' sometimes!
And as a helpless Mukhi was just waiting and hoping that time itself would solve everything, the truth got revealed! And as if that were not enough, Sakshi's attempt to suicide came as a shocking blow to these already helpless couple. So, the last resort to divorce was to come eventually, especially in the mind of Purvi who was already upto some sort of sacrifices.
Yes, these things are not a child's play as you've mentioned. Rather, it takes a lot of guts to sacrifice for love. It doesn't make you any weak or any loser. It makes you strong like no one else. And only unconditional love gives you that strength.
And no, you can't just always ignore the circumstances for the sake of your own happiness. You can't just turn a blind eye to the other sufferers involved.
Yes, being in such kind of a soup, the only visible option left in most of the time is to 'let go' or to 'move on'. That's again a sacrifice. That's again, not easy at all. That can never be actually.
Lastly, the only hope is that "love wins over everything" 🤗
Looking at things from this angle make this situation quite understandable to an extent